This invention relates to a fast curing, thermosetting coating composition. More particularly, the invention relates to polymeric, high solids, fast curing coating compositions adapted to provide an automotive topcoat which demonstrates hardness, high gloss, outstanding durability and excellent resistance to solvents and water. Still more particularly, this invention relates to fast curing, high solids, thermosetting coating compositions adapted to be used as an automotive topcoat wherein the topcoat includes metallic flake as a pigment.
Because of increasingly strict solvent emissions regulations in recent years, low solvent emission paints have become very desirable. A number of high solids paint compositions have been proposed to meet these low solvent emission requirements. However, many of these compositions are deficient because of difficulty in application, slow curing rates, lack of flexibility, poor durability, and low solvent and water resistance. Many of the proposed compositions have been particularly deficient as automotive topcoats, particularly when the topcoat is to include metallic flake as a pigment.
The deficiency in compositions including metallic flake results from undesired reorientation of the metallic flake during application and curing of the coating. The flake reorientation results primarily because of the very low viscosity resins used in the paint compositions to accommodate high solids. The low viscosity is not sufficient to immobilize the flakes which tend to redistribute themselves to show "reverse flop" and nonuniform distribution.
The coating compositions of this invention combine the above discussed desired properties and low application viscosity with rapid cure so as to overcome dificiencies of previously proposed high solids materials and thereby achieve a high solids coating composition particularly adapted for automotive topcoats including metallic flake as a pigment.